[AArch64][SVE2] Asm: support SVE2 Floating Point Pairwise Group

[c-rhodes]

Summary

Patch adds support for the following instructions:

SVE2 floating-point pairwise operations:

• FADDP, FMAXNMP, FMINNMP, FMAXP, FMINP

The specification can be found here:
https://developer.arm.com/docs/ddi0602/latest

[chill]

test/MC/AArch64/SVE2/faddp-diagnostics.s

36 ↗

(On Diff #201217)

Also p0/z is invalid predicate, e.g.:

faddp z0.h, p0/z, z0.h, z1.h
// CHECK: [[@LINE-1]]:{{[0-9]+}}: error: invalid operand

etc.

[c-rhodes]

test/MC/AArch64/SVE2/faddp-diagnostics.s

36 ↗

(On Diff #201217)

I can add a test for that before merging. Managed to miss this for quite a few of the predicate instructions it seems. I have a patch downstream that improves the SVE predicate tests also as similar cases are missing there, I'll get that up after the SVE2 stuff is in.